What is the purpose of the study?

This randomized phase III trial studies rituximab with bendamustine hydrochloride or ibrutinib to see how well they work compared to ibrutinib alone in treating older patients with previously untreated chronic lymphocytic leukemia. Monoclonal antibodies, such as rituximab, can block cancer growth in difference ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer-killing substances to them. Drugs used in chemotherapy, such as bendamustine hydrochloride, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Ibrutinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. It is not yet know whether rituximab with bendamustine hydrochloride is more effective than rituximab and ibrutinib or ibrutinib alone in treating chronic lymphocytic leukemia.